Well that was fast... 5 days after the release of VCSA 6.5.0c, comes 6.5.0d for both Windows & Photon OS versions of vCenter.
Primary reason is bug fix support for VSAN 6.6 that was just released.
vSAN 6.6 Release Notes and the vSAN 6.6 documentation.
The new build is:
Release Date: 2017-04-18
Build Number: 5318154
The new patch is: